The invention relates to a blood treatment machine with a blood treatment component, with a blood line for transporting blood between a patient and the blood treatment component and with control units for monitoring and controlling the blood transport and/or the blood treatment.
Dialysis machines, hemofiltration machines or blood separation machines are known generally as blood treatment machines. Accordingly, dialyzers, hemofilters, plasma filters, adsorbers or blood centrifuges are used as blood treatment components of these machines.
German Patent 37 36 712 C2 describes a generic blood purifying machine. With this known blood purifying machine, various parameters (e.g., composition, temperature and throughput of the dialysis fluid) are controlled and/or regulated by various control devices or controlling elements (e.g., pumps, heaters, valves and pressure regulators) and monitored by appropriate sensors (e.g., temperature sensors, pressure sensors, air bubble sensors).
It is of crucial importance to ensure the functioning of the individual control units, because otherwise life-threatening situations for the patient may occur. To increase functional reliability, redundant computer units, each consisting of a controlling processor unit and a monitoring processor unit, are provided within a control unit, according to German Patent 37 36 712 C2. The control units communicate with one another in a star pattern by way of a main control device, with the controlling processor devices communicating with one another via a central main controlling processor device, and the monitoring processor devices communicating with one another via a central main monitoring processor device.
One disadvantage of this computer architecture of the previously known blood treatment machine, however, is that a failure of a central main processor unit can still lead to a total failure of the blood treatment machine.
The present invention is a system to further increase the functional reliability of the previously known blood treatment machines.
In one embodiment, the invention is thus a blood treatment machine comprising a blood treatment component, a blood line for transporting blood between a patient and the blood treatment component, at least two control units each having an action computer and an auxiliary computer communicating with the action computer, for monitoring and controlling the blood treatment machine, an action bus interconnecting each of the action computers and an auxiliary bus interconnecting each of the auxiliary computers. The invention also includes a table stored in at least one of the action computer or the auxiliary computer in each unit, said table assigning an error processing routine to errors selected from the group consisting of errors occurring in a control unit, errors occurring due to action bus communications or auxiliary bus communications, and error messages received by a control unit. At least one of the action computer and the auxiliary computer is adapted to send an error message to the respective bus as directed by the error processing routine.
The method of the present invention achieves the goal of greater reliability because, unlike a blood treatment machine of the generic type where the action computers are linked together by an action bus and the auxiliary computers are linked together by an auxiliary bus, communication between the action computer and the auxiliary computer is provided by a minimum of two control units.
A table is stored by the action computer and/or by the auxiliary computer in each of the minimum of two control units. In these tables, error cases occurring on the respective control unit and/or due to the bus communication and error messages received by the respective control unit, are assigned to an error processing routine. The action computer and/or the auxiliary computer of a control unit then places an error message on the respective bus as soon as the error processing routine provides for it.
Because of the direct communication connection between the action computer and the auxiliary computer within one control unit, decentralized communication is possible between the individual control units, without failure of an individual control unit leading to failure of the entire blood treatment machine. Depending on the type of communication, the action bus and/or the auxiliary bus may be used, depending on whether the transmitting unit is an action computer or an auxiliary computer.
In contrast with the hierarchical communication system known from German Patent 37 36 712 C2, independent error processing is possible with the invention. According to German Patent 37 36 712 C2, it is assumed that an error message must first be sent to a main controlling processor device or to a main monitoring processor device, and these devices then decide which functions the subordinate units must execute on the basis of the error case. In contrast with that, a table which already contains corresponding error processing routines for the control unit is stored on each control unit according to this invention. With regard to entries in the table, a distinction must be made between error sources occurring on the respective control unit and error messages received by the control unit from the outside over the action bus and/or the auxiliary bus. Error cases can be ascertained by the action computer as well as the auxiliary computer. The error table of one control unit is expediently stored on the action computer as well as on the auxiliary computer.
The blood treatment machine according to the present invention thus includes control units which can be run independently and do not need a higher-level supervisory computer when error sources occur. In this way, each control unit is intrinsically a safe, and can guarantee the security of the task assigned to it.
According to a preferred embodiment, the action computer and the auxiliary computer are each connected to a control unit with measuring sensors and/or controlling elements and measuring sensors. According to another preferred embodiment, the action computer and the auxiliary computer of one control unit for monitoring and controlling components vital to the patient are each connected in parallel to measuring sensors and controlling elements.
According to yet another preferred embodiment of the invention, in safety-critical cases the error processing routine may provide for the respective control unit to be switched to a safe status for the blood treatment independently by their controlling elements which are addressed by the control computer and/or the auxiliary computer.
Although a redundant control approach is pursued for vital components, control of subordinate components may be limited to control by an action computer or an auxiliary computer operating independently. In this way, the available computing power can be utilized optimally without having to curtail the safety of the system.
According to another preferred embodiment, an alarm is triggered in monitoring vital components of the blood treatment machine when the action computer and the auxiliary computer supply different results. Then the blood treatment machine is shut down in such a manner that life-threatening situations for the patient can always be ruled out.
When the blood treatment machine is a dialysis machine, an operating unit, a hydraulic unit and a function unit are preferably provided as control units. The hydraulic unit and the function unit control and monitor vital components of the blood treatment machine, so that the sensors and actuators connected to it are controlled and analyzed by the action computer and the auxiliary computer. For example, a display screen and a keyboard are connected to the action computer of the operating unit, and a status display and an external interface are connected to the auxiliary computer of the operating unit.
The hydraulic unit preferably includes at least one device for processing dialysis fluid, and one for balancing and ultrafiltration, while the function unit includes at least an optical detector, an air detector, an arterial and venous pressure sensor, a blood pump, a heparin pump and a venous clamp.